The invention relates to a system based on GRS for measuring working areas. The system comprises a GPS receiving module, a single chip computer, a memory, a keyboard, a display, a printer and a power supply, wherein the GPS module receives a GPS satellite signal and inputs positioning information into the single chip computer by an RS232 serial port; the single chip computer processes the positioning information and calculates the area of the farmland; the memory stores a working record; by the keyboard and the display, the working fee-charging unit price is input, the date is set, the working route is trimmed, the working area is calculated, and the working record is searched; and the minitype printer prints and outputs the working record. The invention adopts a GPS positioning system tomeasure the working area of the original farmland, adopts the single chip computer to trim the working area of the original farmland and enhances the measurement accuracy of the working area of the farmland.